Soils

Soils

1. Definition

   • Natural body comprised of solids, liquids and gases that occurs on the land surface
     • Characterised by
       • HORIZONS
         • Distinguishable from initial material as a result of additions, losses, transfers and transformations of energy/matter
       • LAYERS
         • OR
         • The ability to support rooted plants in a natural environment

2. Composition

3. Texture

4. Water in soil

   • Water and Soil Chemistry
     • Rainfall, pH and leaching
       • More Rainfall = More Carbonic Acid & Leaching = Low Soil Fertility
         • Acid also released in soil by Humus Decay

5. Cation Exchange Capacity (CEC)

   • Sum of exchangeable cations that a soil can absorb
   • Cation Exchange
     • The interchange between a cation in solution and another cation on a soil surface

6. Soil Horizons

   • Different Lithology and Environmental conditions = Different Soil
     • Soil Regimes
     • Global Soil
     • Zones of Chemical Weathering
     • Weathering Zonation

7. Oxisols/Laterites as a source of Al and Ni

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